Telephone and signaling circuit



F. A. PIGKERNELL. TELEPHONE AND SIGNALING CIRCUIT.

(No Model.)

N0. 534,373. Patented Feb. 19, 1895.

UNITED STATES PATENT OFFICE.

FRANK A. PICKERNELL, OF NEWARK, NEW JERSEY, ASSIGNOR TO THE AMERICANTELEPHONE AND TELEGRAPH COMPANY, OF NEW YORK.

TELEPHONE AND SIGNALING CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 534,373, dated February19,1895.

A plication filed May 3, 1894. Serial No. 509,917- (No model.)

T0 at whom it may concern:

Be it known that I, FRANK A. PICKERNELL, residing at Newark, in thecounty of Essex and State of New Jersey, have invented cer tainImprovements in Telephoneand Signaling Circuits, of which the followingis a specification.

This invention relates to the construction and operation of telephonecircuits, and especially of trunk lines extending between a centralstation and a branch exchange, for the purpose of affording facilitieswhereby telephone connections may be made between the branch exchangeand any substation associated with the said central station withfacility and expedition.

The objects of the invention are to enable a telephone trunk line to beoperated in association with the useful adjuncts, of an order circuit,and a signaling circuit, whereby other lines may at either end of saidtrunk be connected therewith and disconnected therefrom with greatpromptness and speed, the disconnection at one end thereof being causedto automatically announce itself at the tother; and to accomplish thiswithout additional main line conductors for either class of auxiliarycircuit.

In pursuance of these objects my invention consists in a doubleconductor trunk line,

adapted to form a portion of a metallic conversation circuit associatedwith two independent auxiliary circuits, one including the operatorstelephones to, serve as an order or instruction circuit, and the othercontaining signaling appliances and serving as a signal circuit overwhich a disconnection performed at one end of a circuit may be indicatedau-, tomatically at the other; the main conductor of both auxiliarycircuits being constituted of the direct and return conductors of theconversation circuit, considered as one, that is to say connected inparallel with one another.

It also consists in connecting obstruction coils or electro-magneticresistances between the two conductors of the main circuit at theterminal or other stations; in connecting the independent portions ofthe instruction circuit including the operators instruments between thecentral points of the windings of the said obstruction coils, and anindependent return conductor which, if desired, may be the earth; and inconnecting the independent portions of the signaling circuit at onestation between the two main circuit conductors direct, and a suitablereturn conductor, and at the other between the central point of theobstruction coil and the said return conductor through'the signalreceiving device: a current generator being located at any convenientpoint in the said independent portions of the circuit.

It further consist in combining with the above mentioned devices a plugseat switch at one end of the circuit in which the removal andreplacement of a switch plug determines which of the two associatedcircuits shall at any given time be in operative condition; and acircuit closer placed in association with a plug socket or springjack atthe other end of the circuit, and actuated by the insertion orwithdrawal of a plug into or from said socket; and in certain otherdetails of construction and arrangement, to be more fully recitedhereinafter.

In the drawings which accompany this specification Figure 1 is a diagramof an ar-' rangement of circuit conductors and appli ances illustrativeof my invention, and Fig. 2 a diagram of a modification of the same.

A and A are the two conductors of a trunk telephone circuit D, extendingbetween a centralstation 0 and a branch exchange station B; At O theyterminate in adouble conductor switch plug P, and at B in a springjackor plug socket J.

Referring to Fig. 1, at the branch exchange I provide also a plug Pwhich may represent an oflfice trunk or more generally anyof a number ofcircuits (1 which center there and which extend outwardly therefrom totelephone stations S; an operators instruction outfit comprisingtransmitting and receiving telephones T, t, as usual; a key or circuitcloser K controlling the connection of. the said telephones; a visiblesignal device 1; in the normal circuit of the two conductors A and A anda differential obstruction coil or electro-magnetic resistance M bridgedbetween the said main conductors A A and having a connection from thecentral point a of its winding to the stem of the key K. At the centralstation 0 to which may converge local telephone circuits (1 from anynumber of telephone stations S is a similar 6. iferentially woundobstruction coil M a number of multiple connection springjacks or plugsockets J a plug seat switch E which has for a movable element thespring contact I), and for two fixed elements the switch socket f andthe insulated point 0; a branch connection g extending from point 0through a visible signal appliance V and the generator G, which may be abattery, to the earth or other return conductor R and another branchconnection h extending from the switch socket f through an operatorstelephone also to the earth or return conductor B In the normal orquiescent condition of the circuits the metal base of the plug P at thecentral station 0 is in the plug seat or socket E, and the connectionbetween the spring b and the contact 0 is broken by the plug forcingaway the said spring, the telephone 6 being in connection with the trunkcircuit D from ground R wire h, socket casef, spring I), and wire 11;and at the branch exchange B the plug .P is withdrawn. In the operationof connecting two distant substations together the following changes areeffected in the circuits:

We will suppose that the plug P at the branch exchange B has beeninserted into the springjack Jfor the purpose of connecting the circuit(Z with the circuit 01 provided with a terminal switch or spring jack Jat the central station 0. The operator atB notifies the operatorat O toconnect the trunk circuitD with the called for circuit 01 and this isdone by the first operator pressing the key K and speaking to thelistening operatorat central station 0, a circuit beingformed from Ewire 1 telephone 25, secondary 71 of induction coil I, key K, Wire 2 topoint a, where the current is split and part of it traverses wire 3 andthe windings and 51 of the obstruction coil M to the point 5 on theconductor A and there-along to the point 8, and then by wire 10 throughthe windings 52 and 53 of the obstruction coil M to the point (1 Theother part of the current passes by wire 4: through the remainingportion of the winding of the coil M to the point 6 on the conductorAand therealong to the point 7 and then by wire 9 through the secondportion of the winding of the coil M to the point a The current unitingat the point a proceeds by wire 11 to the spring I), through the metalbase of plug P to the metal socket E, and by wire 72. and operatorstelephone 25 to R R and R may be grounded terminals or they may beconnected together by a return wire as indicated. The order having beenreceived over the order circuit by the listening operator, the usualtest is made to ascertain whether the line wanted is busy or not, andbeing found disconnected, the plug P of the trunk D is inserted into thejack J 3 of the called for line and the two stabe any of the well knownforms tions S and S are connected with each other over the followingmetallic circuit: Starting from the tip of plug P (to which one side ofthe circuit d is connected,) to spring 13 of jack J, conductor A oftrunk D, to the tip of plug P, spring 19 ofjack J and to and fromtelephone S by the circuit d to the frame 20 of jack J sleeve of plug P,conductor A of trunk D, spring 12 of jack J, sleeve of plug P to theother side of circuit d. When the plug P is inserted into jack J thespring 15 is lifted from the contact 16 and rests on the insulation 18and the ground wire '17 is sev" ered at that point, and at the same timethe elevation of the spring 13 upon the tip of the plug separates thespring from the contact 14 and thereby opens the branch circuit whichcontains the visible signal 1;. The conversation being concluded betweenthe stations S and S notice thereof is given in any preferred manner tothe operator at the branch exchange 13, who thereupon withdraws the plugP from the jack J allowing the springs 13 and 15 to close upon theirrespective contacts 14 and 16 and to connect the ground branch wire 17once more to the circuit D. The effect of connecting the grounded branch17 is to operate and set the disconnecting signal V at the centralstation 0 by means of current from battery G, to notify the operatorthere of the termination of conversation between the stations S and Sand of the readjustment of the circuit at the branch exchange. This willbe seen by tracing the circuit from R, wire 17, contact 16, spring 15 tothe point 21, the main circuit for the current being from this point byconductor A to point 7 and by Wire 9 and the winding of the coil M topoint a a smaller current passing from point 21 by spring 13, contact 14through the visible signal 1) (but not enough owing to its resistance tooperate it) and by conductor A to point 8, and by wire 10 through thewindings 52 and 53 ofthe coil M to the point a and by wire 11 to springb, thence to contact 0, wire g, disconnecting signal V and battery G toground R The operator at the central station 0 in response to the noticegiven by the signal V withdraws the plug P from the jack J and replacesit in the plug socket switch E thereby forcing the spring 19 away fromthe contact 0 and thus opening the circuit, and resetting the signal V,which may of self setting visible signals. 7

The trunk circuitD is provided with spring jacks J connected in parallelwith its conductors by the wires 22 and 23 by means of which the centralstation 0 can connect with the branch exchange B, and the annunciatordrop 1: is provided at the said exchange to indicate to the operatorthere that the central exchange wishes to communicate, the said drop '0being operated by an alternating current, from the generator at thecentral station in a manner well understood.

In the modification shown in Fig. 2the cir- IIO tional battery G2 andobstruction coil M is connected with the wire 2 at the branch exchangeB. The coil M prevents the telephone current in the ordering circuitfrom short circuiting between the grounds R R The batteries G and G havelike poles connected to the trunk circuit D so that when the plug P isWithin the jack J, and the signal circuit is open, there is no flow ofcurrent from one to the other, but when the plug P is withdrawn from thejack J the circuit is closed and the current from the two batteriespasses in multiple upon the trunk lines A and A with respect only to theground R at the branch exchange, and the signal V is thus operated bythe battery G alone, as will be readily seen from the foregoingdescription of the operation of the signal of Fig. 1.

Having thus described my invention and its mode of operation, Iclaim- 1. In a telephone system, the combination of a trunk lineextending between two stations and having two conductors adapted to formportions of the going and return conductors of a metallic conversationcircuit, means at the terminals of said trunk line for connecting thesame at will with any subscribers station, an independent instructioncircuit including operators telephones, and an independent signalingcircuit including suitable signal-sending and receiving devices, the twoconductors of the said trunk-line constituting jointly the main line, ordirect conductor of the said instruction and signaling circuits,substantially as described.

2. In a telephone system a main telephone or conversation circuit havingtwo'conductors, serving respectively as its direct and re-' turnconductors; combined with two obstruction coils or electromagneticresistances connected respectively between the said direct and returnconductors of the said main circuit at each of two selected stationsthereof; an instruction circuit extending between the said two selectedstations and composed of a direct conductor formed of the two conductorsof the main circuit joined in parallel, the winding of the twoobstruction coils from their two ends to their centers, and anindependent return conductor uniting the central points of the said twoobstruction coil windings, and including the telephones at each of thesaid stations; and a signaling circuit between the said stationscomprising the said two'main line conductors joined in parallel theobstruction coil winding at one of the said stations from its two endsto its center, and a return conductor extending from the said centerthrough a signal receiving device, and an electrical generator to aconnection with the two main line conductors at the other of saidstations, substantially as described.

3. The combination of two main line conductors extending between twostations and terminating, at one in a double conductor switch plug, andat the other in a switch socket or springjack; an obstruction coil ateach station connected between the said two conductors; a plug seatswitch at the switch plug terminal station, comprising a movable and twofixed members and operated by the removal and replacement of the plug; aconductor extending between the movable member of said switch and thecentral point of the obstruction coil winding at the said station; anormally discontinuous return conductor extending from the central pointof the obstruction coil winding at the socket terminal station through acircuit closer, and the station telephones, to one of the fixed membersof said switch; a normally continuous return conductor extending from aseparable connection at the plug socket station formed in said socketand adapted to be separated by the insertion of the plug therein, to theremaining fixed member of the plug seat switch at the other station, anda signal receiving device and generator included therein at said otherstation; whereby the said two main line conductors may serve separatelyas the direct and return conductors of a double wire conversationcircuit and together as the direct conductor of independent instructionand automatic signaling circuits, substantially as specified.

In testimony whereof I have signed my name to this specification, in thepresence of two subscribing witnesses, this 30th day of April, 1894. p

FRANK A. PIGKERNELL. Witnesses:

THos.'D. LOCKWOOD, JOSEPH A. GATELY.

